The present invention relates to a drawing management device for managing the drawings of facilities, such as a pipe laying system of a water and gas supply, a wiring system for electric power and telephone, a road for vehicles, etc., in the form of digitized information. It should be noted that the term `drawing` as used herein refers to a drawing of the facility, such as a water supply, a machine design drawing, a road traffic map, etc.
Traditionally, the state of facilities, such as a pipe system for water and gas supply, and a wiring arrangement for electric power and telephone communication, has been provided in the form of a drawing drafted on a sheet of paper or polyester film. In this case, each change in the facilities requires a modification to be made to the drawing. The work of modifying the drawing must be performed manually with the result that a long time and much labor are required and also the possibility that errors will be made in modifying the drawing is relatively strong. In order to solve such a problem, it has been proposed to manage the facility drawing in the form of its digitized information. More specifically, as disclosed in JP-A-63-254565, the management is performed by displaying the many facility drawings (e.g., topography drawings, system drawings and symbol drawings) stored is digital data in a file device on a display device under computer control. The work for modifying the drawings is also made under computer control for the drawings displayed on the display device.
However, the above prior art has the following defects. In displaying large scale drawing data including e.g. qualifying lines, the processing therefor is executed at a very low speed since the data amount to be drawn or displayed during a unit time is very large. This is because even if only a part of the drawing is required, all the data including minute and detailed character information, which is difficult to recognize, are displayed. Therefore, the above prior art system is poor in its usability and efficiency as a facility display system.
The present invention has been accomplished in order to eliminate the above defect of the prior art, and intends to provide a drawing management device that can surely attain a user (operator)'s objectives, i.e. has a function of displaying the object required by a user swiftly and exactly. This is because, where very detailed drawing information is not necessary, it is important to display only the drawing information within the range required by an operator as soon as possible, but not all of the items of the stored detailed drawing information.